Drive belt Tensioner Pulley replacement

3.0L or 3.3l is the same. You'll see a square hole in the tensioner.
That is for a long tool to help take off the tension so the belt can come off. A 15 mm nut may also be there for some vehicles, it needs a long handle. After that, it is easy. Usually, the pulley is held on by 15 mm bolts and a nut or two from behind. Battery unhooked. ok It is an easy job, with that serpentine belt tool. At most Auto stores. Glad your keeping it in good shape. That belt does a lot of work.
See the guide below on replacing a belt tensioner- not vehicle specific, but will give you an idea

https://www.2carpros.com/articles/serpentine-belt-tensioner-replacement

Diagram below shows the arrangement on the front of the engine

Put wrench on that bolt in middle of pully